SUM
语法：
SUM(expr)
功能：分组求和。

说明：expr必须是能够转为NUMBER的表达式。

示例：

返回staffS表中工资总和。
CREATE TABLE  staffS
(
  staff_ID    NUMBER(6) not null,
  FIRST_NAME     VARCHAR2(20),
  LAST_NAME      VARCHAR2(25),
  EMAIL          VARCHAR2(25),
  PHONE_NUMBER   VARCHAR2(20),
  HIRE_DATE      DATE,
  employment_ID         VARCHAR2(10),
  SALARY         NUMBER(8,2),
  COMMISSION_PCT NUMBER(2,2),
  MANAGER_ID     NUMBER(6),
  section_ID  NUMBER(4)
);
INSERT INTO  staffs (staff_ID, FIRST_NAME, LAST_NAME, EMAIL, PHONE_NUMBER, HIRE_DATE, employment_ID, SALARY, COMMISSION_PCT, MANAGER_ID, section_ID)
VALUES (198, 'Donald', 'OConnell', 'DOCONNEL', '650.507.9833', to_date('21-06-1999', 'dd-mm-yyyy'), 'SH_CLERK', 2600.00, null, 124, 50);

INSERT INTO  staffs (staff_ID, FIRST_NAME, LAST_NAME, EMAIL, PHONE_NUMBER, HIRE_DATE, employment_ID, SALARY, COMMISSION_PCT, MANAGER_ID, section_ID)
VALUES (199, 'Douglas', 'Grant', 'DGRANT', '650.507.9844', to_date('13-01-2000', 'dd-mm-yyyy'), 'SH_CLERK', 2600.00, null, 124, 50);

INSERT INTO  staffs (staff_ID, FIRST_NAME, LAST_NAME, EMAIL, PHONE_NUMBER, HIRE_DATE, employment_ID, SALARY, COMMISSION_PCT, MANAGER_ID, section_ID)
VALUES (200, 'Jennifer', 'Whalen', 'JWHALEN', '515.123.4444', to_date('17-09-1987', 'dd-mm-yyyy'), 'AD_ASST', 4400.00, null, 101, 10);
SELECT SUM(SALARY) AS "SUM" FROM staffs;

SUM
----------------------------------------
9600

1 rows fetched.
STDDEV
语法：
STDDEV(expr)
功能：分组求样本标准差，作为聚集函数或分析函数。

示例：

返回staffS表中工资的标准差。
CREATE TABLE  staffS
(
  staff_ID    NUMBER(6) not null,
  FIRST_NAME     VARCHAR2(20),
  LAST_NAME      VARCHAR2(25),
  EMAIL          VARCHAR2(25),
  PHONE_NUMBER   VARCHAR2(20),
  HIRE_DATE      DATE,
  employment_ID         VARCHAR2(10),
  SALARY         NUMBER(8,2),
  COMMISSION_PCT NUMBER(2,2),
  MANAGER_ID     NUMBER(6),
  section_ID  NUMBER(4)
);
INSERT INTO  staffs (staff_ID, FIRST_NAME, LAST_NAME, EMAIL, PHONE_NUMBER, HIRE_DATE, employment_ID, SALARY, COMMISSION_PCT, MANAGER_ID, section_ID)
VALUES (198, 'Donald', 'OConnell', 'DOCONNEL', '650.507.9833', to_date('21-06-1999', 'dd-mm-yyyy'), 'SH_CLERK', 2600.00, null, 124, 50);

INSERT INTO  staffs (staff_ID, FIRST_NAME, LAST_NAME, EMAIL, PHONE_NUMBER, HIRE_DATE, employment_ID, SALARY, COMMISSION_PCT, MANAGER_ID, section_ID)
VALUES (199, 'Douglas', 'Grant', 'DGRANT', '650.507.9844', to_date('13-01-2000', 'dd-mm-yyyy'), 'SH_CLERK', 2600.00, null, 124, 50);

INSERT INTO  staffs (staff_ID, FIRST_NAME, LAST_NAME, EMAIL, PHONE_NUMBER, HIRE_DATE, employment_ID, SALARY, COMMISSION_PCT, MANAGER_ID, section_ID)
VALUES (200, 'Jennifer', 'Whalen', 'JWHALEN', '515.123.4444', to_date('17-09-1987', 'dd-mm-yyyy'), 'AD_ASST', 4400.00, null, 101, 10);
SELECT STDDEV(SALARY) AS "STDDEV" FROM staffs;

STDDEV
----------------------------------------
1039.23048454132637611646780490352342017

1 rows fetched.